The present invention relates to a method of forming an isolation layer of a semiconductor device, and more particularly relates to a method of forming an isolation layer of a semiconductor device for gap-filling a trench without generating a void.
As semiconductor devices become more highly integrated, the width of trenches becomes more narrow and the depth of trenches becomes more deep. As such, it is more difficult to completely gap-fill a trench with a conventional high density plasma (HDP) oxide layer to form an isolation layer, without generating a void. To solve the aforementioned problem, the material used for gap-filling the trench without generation of voids has been actively studied.
To solve the above-described problem, polysilazane (PSZ) material is placed in the trench to partially fill a lower portion of the trench, and high density plasma (HDP) oxide layers having a stacked structure are formed on the polysilazane (PSZ) material in a stacked structure to fill completely the trench.
However, if the high density plasma (HDP) oxide layers having a stacked structure are formed on polysilazane (PSZ) material in a stacked structure, since the high density plasma (HDP) oxide layer is porous, etchant solution can flow down to the polysilazane (PSZ) material through the porous high density plasma (HDP) oxide layers during a subsequent etching process. As a result, polysilazane (PSZ) material is exposed and a void is generated in the polysilazane (PSZ) material.